69 the more evolved the brain is, the more pleasurable sex is.
That being said, it doesn't mean humans are the only ones who experience sexual pleasure.
Of course animals masturbate, it's only natural (even foetus do).
Cats do that all the time, I really don't understand the point of writing this story here.
When you have a cat, you learn to keep your sweaters and blanckets out of its reach.
I still think it's better than being humped by a dog.